Device for adapting the size of a machine tool jaw

ABSTRACT

A device that includes a frame equipped with guiding means, blank holder modules to be moved along the guiding means, means for blocking independently each blank holder module in a specific position, a magazine of end modules located near each end of the guiding means and gripping and handling means for grasping an end module to fix the end module to a blank holder module and vice-versa.

This application is a 371 of PCT/FR97/01227, filed Jul. 7, 1997.

The present invention relates to a device for adapting the size of ajaw.

BACKGROUND OF THE INVENTION

A jaw is a machine tool part designed for machining elements in the formof sheets, such as sheet metal, that holds the machined sheet firmly.Jaws are found, for example, in drawing machines and bending brakes.

The size of the jaw must be adapted to the size of the sheet metal to bemachined and to the operation carried out. To be able to machine piecesof sheet metal of different sizes on the same machine tool, it isnecessary to be able to change the size of the jaw.

Adapting the entire jaw to the size of the sheet metal to be machinedwithout manual intervention is known.

The main drawback of conventional systems for adapting the size of a jawautomatically is that this operation takes a relatively long time, thuslimiting productivity in relation to flexibility. The time required tomachine the sheet metal is less than the time taken to adapt the jaw inknown systems. Hence, a user will endeavor to fabricate several partswith the same size before changing the size of the jaw.

Moreover, for optimization reasons, manufacturers recommend firstrunning operations requiring a short jaw on the machine tool equippedwith a modular jaw, and subsequently, running operations requiring along jaw. The user, thus, has to adjust the machining sequence to theseconstraints.

SUMMARY OF THE INVENTION

The goal of the invention is to furnish a device enabling the size of ajaw to be adapted very rapidly to improve the flexibility of a machinetool designed to receive this jaw and enable the various machiningoperations to be conducted in any sequence without thereby affectingcycle time.

For this purpose, the device it proposes consists of a frame providedwith guide means, jaw modules designed to move along the guide means,means for independently locking each jaw module into a given position, amagazine of end modules located near each end of the guide means andgripping and handling means for gripping an end module in a magazine toposition the end module against a jaw module and withdraw an end modulepositioned against a jaw module to replace it in a magazine.

The configuration of the jaw can then be changed very rapidly. One needonly move the jaw modules not used for making a predefined bend towardthe ends of the guide means and regroup the jaw modules needed for thisbending operation at the center of the guide means then, with the aid ofgripping means, bring an end module to each end of the group of jawmodules to form a jaw of the desired size for making the bend. All theseoperations can be conducted rapidly, because the jaw modules can move atthe same time as the end modules.

Advantageously, a module, called a central module, is mounted in a fixedposition relative to the frame. The movable jaw modules are located oneach side of the central module. The jaw modules on a given side of thecentral module are all similar, and the jaw modules on one side of thecentral module have a different length in the direction of the guidemeans than those located on the other side of the central module. Thecentral module then serves as a stop when the jaw modules are beingmoved. The different lengths of the jaw modules on one side and on theother side of the central module enables a greater variety of differentjaw lengths to be offered. If, for example, all the jaw modules and thecentral module are 100 mm long, the assembly formed by the jaw modulesand the central module will always be a multiple of 100 mm long. On theother hand, if the jaw modules on one side are 100 mm long and those onthe other side are 50 mm or 150 mm long, it will also be possible tohave total lengths that are multiples of 50 mm. Of course, other valuesand other length ratios are possible.

In a preferred embodiment, the guide means are comprised of at least onerectilinear rail integral with the frame. In this case, advantageously,the jaw modules are mounted on two parallel rails between which isguided a drive bar, and the locking means enable each jaw module,independently of the others, to be coupled to either the drive bar orthe guide rails. To move the jaw modules, one need only join them to thedrive bar and move the latter with these modules. The other jaw modulesthat are not supposed to move remain coupled to the frame. To shift allthe jaw modules that are to be moved, one need only move the drive baronce in one direction with the modules moving in the same direction,then move the jaw modules that are supposed to move, in the otherdirection.

In a preferred embodiment, each jaw module has a locking part that canmove perpendicularly to the guide rails. The locking part has a U-shapedsection perpendicularly to the guide rails with the end of one arm ofthe U being in a lengthwise groove provided in a rail. The other arm endof the U is opposite the other guide rail and the drive bar projectsbetween these two arms. A spring pretensions the locking part in onedirection making the locking part coupled to the frame or the drive bar.An actuator is provided to act against the spring to make the lockingpart coupled to the drive bar or the frame.

To drive the drive bar, it is provided with a rack meshing with a geardriven by a motor. Other means are of course possible: the bar can, forexample, be connected to an actuator or to a linear motor.

In the device according to the invention, the gripping and handlingmeans may be a gripper moving lengthwise on the frame. Other solutionssuch as a manipulator robot are also possible.

The invention also proposes using a device such as that described aboveon a machine designed to make bends in a piece of sheet metal, havingtwo jaws and one bending tool. In such a machine, there is no point inhaving two modular jaws; a single jaw is generally sufficient.

Such a machine, or bending brake, can adapt the size of its jaw duringthe time taken for the bent piece of metal to leave and the metal to bebent to take its place. For sheets to be bent on two opposite sides, theinvention proposes a machining center, characterized by having twobending brakes according to the invention, the two bending brakes beingopposite each other and able to move toward or away from each other, andby a conveyor designed to convey the pieces of sheet metal being locatedbetween the two bending brakes. The conveyor can also be provided with acentral rotator which is placed between the two bending brakes and isable to turn the sheets to be bent on four sides—or more.

In any event, the invention will be properly understood with the aid ofthe description that follows with reference to the attached schematicdrawings that show a device according to the invention as a nonlimitingexample.

BRIEF DESCRIPTION OF THE DRAWINGS

Embodiments of this invention will be described in detail, withreference to the following drawings wherein like numerals represent likeelements and wherein:

FIG. 1 shows a machine designed to bend pieces of sheet metal, providedwith a device according to the invention,

FIGS. 2 and 3 are schematic front views showing the device in twodifferent positions,

FIG. 4 shows a drive mechanism for jaw modules,

FIG. 5 is a cross section on an enlarged scale along line 5—5 in FIG. 4,

FIG. 6 is a cross section on an enlarged scale along line 6—6 in FIG. 4,

FIGS. 7 to 10 represent several possible configurations of a deviceaccording to the invention,

FIG. 11 shows in a side view two bending brakes opposite each other,each of them provided with a device according to the invention, and

FIG. 12 is a perspective view of an end module.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

As one application example of a device for adapting the size of a jaw,FIG. 1 shows a sheet metal bending brake provided with such a device.

This bending brake has a bench 2, a brush table 4 designed to receive asheet of metal (not shown in this figure) to be bent, a bending tool 6,a fixed lower jaw 8, an upper jaw 10 mounted on an arm 12 pivotingaround an axis 14, and a manipulator robot 16 to move the sheets to bebent.

The width of upper jaw 10 is modular. Thus, the bending brake can beadapted to numerous sheet dimensions and several types of bending. Themeans whereby the size of jaw 10 is modified are described below.

FIGS. 2 and 3 show schematically upper jaw 10 of the bending brake ofFIG. 1 and the device that varies its width. Jaw 10 has several jawmodules 18, 19, all of similar

These modules are guided on the two parallel rails 22. Between these tworails 22 is a space forming a groove in which a drive bar 40 is guided.This drive bar 40 is provided with a rack 42 at one of its ends, withwhich a gear 44 driven rotationally by a motor (not shown) meshes.

Each jaw module 18, 19 is provided with a device that either joins it torails 22 or joins it to drive bar 40. When drive bar 40 moves, it bringswith it the jaw modules 18, 19 attached to it, the others remainingstationery. Thus, it is possible to move each jaw module individually,or in a group of jaw modules, or any other conceivable combination.

FIGS. 5 and 6 show a cross section of a jaw module 18 and its associatedlocking device. The latter comprises in particular a locking part 46, aspring 48, and a pneumatic actuator 50.

Locking part 46 is placed in a recess provided in the side of the jawmodule that faces rails 22. This recess is such that the locking partcan move perpendicularly to rails 22. In a sectional plane perpendicularto rails 22 (FIGS. 5 and 6), locking part 46 has a generally U-shapedcross section. The arms of the U point to rails 22. The end of a firstarm fits into a groove 52 provided longitudinally in a rail 22. Thesecond arm faces the other guide rail 22. Drive bar 40 projects from thetwo rails 22 and is located between the two arms of locking part 46. Thesecond arm of this part 46 faces drive bar 40.

At its first arm, the locking part is subjected to the action of spring48, which urges the first arm of the locking part toward drive bar 40.At the second arm is pneumatic actuator 50. The latter can urge lockingpart 46 against spring 48 and thus push the second arm in the directionof drive bar 40.

FIG. 5 shows the position of jaw module 18 when actuator 50 is notacting. Spring 48 then urges locking part 46 toward drive bar 40. Thefirst arm of this locking part 46 then abuts the wall of groove 52provided in a rail 22. By reaction, jaw module 18 moves in the oppositedirection, namely leftward in FIG. 5. Module 18 then abuts the outerface of rail 22 opposite spring 48. Thus, the jaw module is locked ontothe two rails 22 and is thus coupled to frame 20.

FIG. 6 shows the position of jaw module 18 when actuator 50 acts.Actuator 50 then pushes locking part 46 so that its second arm abutsdrive bar 40. By reaction, jaw module 18 moves in the direction oppositeto the direction of movement of locking part 46, namely rightward inFIG. 6. The dimensions of the various guide grooves guiding jaw module18 on rails 22 are such that jaw module 18 then abuts drive bar 40, notrail 22 opposite pneumatic actuator 50. Thus, jaw module 18 is coupledto drive bar 40.

FIGS. 7 to 10 show several possible jaw configurations, among numerousothers, obtained by associating jaw modules 18, 19 with end modules 36,37. FIG. 7 shows a configuration in which all the jaw modules 18, 19 aregrouped around central module 28 and an end module 36, 37 is located ateach end.

FIG. 8 shows another configuration. When changing from the configurationof FIG. 7 to that of FIG. 8, several steps are necessary, but they canbe effected very rapidly. End modules 36, 37 are first replaced in theirrespective magazines. The three leftmost jaw modules 18 in FIGS. 7 and 8are coupled to drive bar 40. The latter is moved leftward. The pressurein actuators 50 corresponding to these three jaw modules 18 is released.These modules thus become coupled to rails 22 and are fixed relative toframe 20. The three rightmost jaw modules 19 in FIG. 7 are then coupledto drive bar 40, subjecting the corresponding actuators 50 to pressure.All the other jaw modules 18, 19 remain coupled to rails 22 and arefixed relative to frame 20. Drive bar 40 moves rightward, bringing withit the three jaw modules 19.

While these movements of jaw modules 18, 19 are taking place, grippers26 grip each end module 36, 37 in a corresponding magazine 24, 25 andposition it on module 18, 19 forming the end of the jaw.

If, in the bending operation to be carried out by the bending brake, itis not necessary to have an end module at the end of the jaw, endmodules 36, 37 can remain in place and be between two jaw modules 18,19, as shown in FIG. 9. The time necessary for changing theconfiguration can then be slightly reduced.

FIG. 10 shows a configuration in which an end module 37 is placeddirectly on central module 28. Thus, it is possible to have a narrowjaw.

By judiciously choosing the widths of jaw modules 18, 10 and end modules36, 37, it is possible to cover an entire range of widths for the jawobtained with a predetermined incrementation. The dimensional example,indicated below, enables all widths multiples of 5 mm to be obtained,starting at the width of 310 mm.

Thus, for example, one can choose jaw modules 18 with a width of 100 mm,which in the example shown in the drawing are at the left of centralmodule 28, jaw modules 19 with a width of 150 mm, which will be to theright of central module 28, four end modules 36 associated with magazine24 and hence destined to be mounted on jaw modules 18 with dimensions 80mm, 90 mm, 100 mm, and 105 mm, and four end modules 37 associated withmagazine 25 and hence destined to be mounted on jaw modules 19,measuring 80 mm, 85 m, 95 mm, and 105 mm. If, as shown in FIGS. 7 to 10,the jaw has five 100 mm jaw modules 18 and four 150 mm jaw modules 19,it is possible to assemble the various modules 28, 18, 19, 36, 37 toobtain any jaw width that is a multiple of 5 mm and is between 310 mmand 1310 mm.

Of course, the movement of grippers 26 and drive bar 40 can becontrolled by a computer (not shown) which, depending on the necessaryjaw width and the type of bend to be created, calculates theconfiguration to be adapted and the paths of the various elements, thensupplies this information to a central control system that controls themovement of these elements.

The design of the modular jaw as described above allows a very rapidtransition from one configuration to the next, lasting about tenseconds. Thus, it becomes possible to change the configuration at thesame time as changing the sheet metal or the position of this sheet.Contrary to machines known to date, which require about ten times thesetup time, the jaw configuration can be changed without taking extratime.

It then becomes conceivable to place two bending brakes opposite oneanother, as shown in FIG. 11. A conveyor, not shown, brings a piece ofsheet metal 54 to a position between the two bending brakes. A centralrotator 56 is located between the two bending brakes to rotate a sheetof metal that is to be bent on four sides, or more. Of course, to adaptto the various dimensions of the sheet and the type of bend to be made,the two bending brakes must be able to move away from and toward eachother. For this purpose, they are both mounted on a common base 58. Acomputer and a central control system can be provided to calculate andcontrol the movements of the two machines on common base 58, but theycan also control the modular jaws of the two machines.

It goes without saying that the invention is not confined to theembodiment described above as a nonlimiting example; on the contrary itcovers all variants.

Thus, for example, each jaw module could be equipped with drive meansenabling it to move by itself on the guide means. The drive bar would bereplaced by a fixed rack extending over the entire length of the frameand each jaw module would be equipped with a motor with a gear at theend of its shaft. A brake would prevent the gear from turning, thus,locking the module onto the frame. The modules could be guided on guidecolumns.

The device enabling the size of a jaw to be adapted is not necessarilyadapted to a bending brake a machine for bending around a specificradius. It can be mounted on any machine having a jaw such as a machineused to bend at an angle.

The size, shape, and number of the modules are provided only as examplesto illustrate the invention. It is of course possible to multiply thenumber of modules to increase the number of possible configurations.

What is claimed is:
 1. A device that adjusts a size of a jaw, the devicecomprising: a frame provided with guides, jaw modules that move alongthe guides, means for independently locking each jaw module into a givenposition, a magazine of end modules located near each end of the guides,gripping and handling means for gripping an end module in the magazineto fit the end module on the jaw module and reposition the end modulefitted on the jaw module to replace the end module in the magazine. 2.The device of claim 1, further comprising: a central module mounted in afixed position relative to the frame, wherein, the movable jaw modulesare located on opposite first and second sides of the central module,the movable jaw modules on the first side of the central module allbeing similar and the jaw modules on the second side of the centralmodule having a different length in a direction towards the guides thanthe movable jaw modules located on the first side of the central module.3. The device of claim 1, wherein the guides are comprised of at leastone rectilinear rail coupled to the frame.
 4. The device of claim 3,further comprising: two parallel rails on which the movable jaw modulesare mounted; a drive bar guided between the two parallel rails; andlocking means that enable each movable jaw module independently of theother movable jaw modules, the locking means coupled to the drive bar orthe guides.
 5. The device of claim 4, wherein, each jaw module has alocking part that moves perpendicularly to the guides, the locking parthaving a U-shaped section, perpendicular to the guides, with an end ofone arm of the U being in a lengthwise groove provided in one of theguides, an other arm end of the U being opposite one of the otherguides, and the drive bar projecting between the two arms of the U, thedevice further comprising a spring and an actuator, the springpretensions the locking part in one direction, making the locking partpositioned next to the frame or the drive bar, the actuator acts againstthe spring to position the locking part next to the drive bar or theframe.
 6. The device of claim 4 wherein, the drive bar includes a rackand the device further comprises a gear and a motor that drives thegear, the gear meshing with the rack of the drive bar.
 7. The device ofclaim 1, wherein the gripping and handling means is comprised of agripper moving lengthwise on the frame.
 8. A machine that bends sheetmetal, the machine comprising: a plurality of jaws; a bending tool; anda device that adjusts the size of the jaw according to claim
 1. 9. Thedevice of claim 2, wherein the guides are comprised of at least onerectilinear rail coupled to the frame.
 10. The device of claim 9,further comprising: two parallel rails on which the movable jaw modulesare mounted; a drive bar guided between the two parallel rails; andlocking means that enable each movable jaw module independently of theother movable jaw modules, the locking means coupled to the drive bar orthe guides.
 11. The device of claim 10, wherein, each jaw module has alocking part that moves perpendicularly to the guides, the locking parthaving a U-shaped section, perpendicular to the guides, with an end ofone arm of the U being in a lengthwise groove provided in one of theguides, an other arm end of the U being opposite one of the otherguides, and the drive bar projecting between the two arms of the U, thedevice further comprising a spring and an actuator, the springpretensions the locking part in one direction, making the locking partpositioned next to the frame or the drive bar, the actuator acts againstthe spring to position the locking part next to the drive bar or theframe.
 12. The device of claim 5 wherein, the drive bar includes a rackand the device further comprises a gear and a motor that drives thegear, the gear meshing with the rack of the drive bar.
 13. The device ofclaim 10 wherein, the drive bar includes a rack and the device furthercomprises a gear and a motor that drives the gear, the gear meshing withthe rack of the drive bar.
 14. The device of claim 11 wherein, the drivebar includes a rack and the device further comprises a gear and a motorthat drives the gear, the gear meshing with the rack of the drive bar.15. The device of claim 2, wherein the gripping and handling means iscomprised of a gripper moving lengthwise on the frame.
 16. The device ofclaim 3, wherein the gripping and handling means is comprised of agripper moving lengthwise on the frame.
 17. The device of claim 4,wherein the gripping and handling means is comprised of a gripper movinglengthwise on the frame.
 18. The device of claim 5, wherein the grippingand handling means is comprised of a gripper moving lengthwise on theframe.
 19. A machining center, comprising: a first machine that bendssheet metal, the first machine comprising: a first plurality of jaws; afirst bending tool; a first frame provided with first guides; a firstjaw modules that move along the first guides; a first means forindependently locking each first jaw module into a given position; afirst magazine of first end modules located near each end of the firstguides; and a first gripping and handling means for gripping a first endmodule in the first magazine to fit the first end module on the firstjaw module and reposition the first end module fitted on the first jawmodule to replace the first end module in the first magazine; a secondmachine that bends sheet metal, wherein the first and second machinesare positioned opposite each other and movable toward or away from eachother, the second machine, comprising: a second plurality of jaws; asecond bending tool; a second frame provided with second guides; asecond jaw modules that move along the second guides; a second means forindependently locking each second jaw module into a given position; asecond magazine of second end modules located near each end of thesecond guides; and a second gripping and handling means for gripping asecond end module in the second magazine to fit the second end module onthe second jaw module and reposition the second end module fitted on thesecond jaw module to replace the second end module in the secondmagazine; and a conveyor that conveys pieces of sheet metal, theconveyor located between the two machines.
 20. The machining center ofclaim 19, wherein the jaws, hold the pieces of sheet metal and themachining center further comprises a central rotator that rotates thepieces of sheet metal to bend the pieces of sheet metal held by thejaws, the central rotator being located between the two machines.